(a) Name two artificial satellites. (b) A geostationary satellite moves in an orbit of radius 6300 km. Calculate the speed with which it moves in the orbit....

Answer Details

(a) Two artificial satellites. A communication satellite and a weather (meteorological) satellite. (Other acceptable examples: a navigation/GPS satellite, a spy/reconnaissance satellite, the International Space Station.)

(b) Speed of the geostationary satellite. A geostationary satellite has the same period as the earth's rotation, so its period is

\[ T = 24\ \text{hours} = 24\times 60\times 60 = 86400\ \text{s} \]

Radius of orbit \(r = 6300\ \text{km} = 6.3\times10^{6}\ \text{m}\).

The satellite moves once round the circular orbit (circumference \(2\pi r\)) in time T, so its orbital speed is

\[ v = \frac{2\pi r}{T} = \frac{2\times\frac{22}{7}\times 6.3\times10^{6}}{86400} \] \[ v = \frac{39\,600\,000}{86400} \approx 458\ \text{m s}^{-1} \]

The satellite moves in its orbit with a speed of about 458 m s\(^{-1}\).